Lead Software Engineer (.Net Core + LLM's

Lead Software Engineer (.Net Core + LLM's)

Aperia Solutions is a leading payments SaaS company headquartered in Dallas, Texas. We build risk management, residuals accounting, compliance, and analytics platforms used by merchant banks, ISOs, payment processors, and other participants in the credit card payments ecosystem. Operating under PCI DSS 4.0 compliance across dual on-premises datacenters (Allen, TX and Chicago, IL) plus Azure cloud, we process high-volume payment data for some of the industry's largest players.

We're in the middle of a significant platform modernization program: a next-generation risk analysis and scoring platform on Microsoft Fabric, an AI-powered ingestion platform, new AI-native applications, and ongoing evolution of the products our clients rely on every day. The teams executing this work are deliberately small and senior, with executive-level support and minimal bureaucracy. Every senior hire is a founding contributor to the architecture and the code.

This is a hands-on technical leadership role spanning the breadth of Aperia's product portfolio: the risk platform build, the AI-powered ingestion platform, our residuals and compliance products, client-facing web applications, and a new Lang Graph-based agentic application. You'll report directly to the SVP of Research & Development and act as the connective tissue across these work streams — leading implementation, driving code-level design decisions, and reviewing designs and code across teams.

This is not a people-management position, and you won't be working alone at the whiteboard — Aperia has dedicated architects who own the big-picture system design. Your job is to turn that design into shipped, production-quality software and to set the engineering standard for how it gets built. You'll lead the risk platform build team — a Senior Data Platform Engineer, a Senior Dev Ops engineer, and a mid-level developer — while spending most of your time in the code yourself: shipping production C#/.NET

services, building React frontends, and contributing to our Python-based agentic work. You lead by technical judgment and example, working closely with our architects where work streams meet.

What You'll Do

• Lead implementation across multiple concurrent projects — translate architecture from our dedicated architects into technical plans, code-level designs, and shipped software.
• Design and ship production C#/.NET services and REST APIs serving high-volume payment data under PCI DSS constraints.
• Build and evolve client-facing web applications in React and Type Script, from component architecture through API integration.
• Contribute hands-on to our Lang Graph-based agentic application — agent orchestration, tool integration, and the engineering discipline (testing, evals, observability) that makes LLM-powered systems production-worthy.
• Own engineering standards across teams: code review culture, automated testing discipline (unit, integration, end-to-end), and CI/CD practices in Azure Dev Ops.
• Deploy and operate services on AKS across Azure and our dual on-premises datacenters, partnering with Dev Ops on infrastructure and release engineering.
• Mentor the engineers on your team — data platform, Dev Ops, and application developers — through code review, pairing, and design collaboration.
• Champion AI-assisted development (Claude Code, Cursor, Git Hub Copilot) — help define, document, and enforce team standards for using these tools well.
• Participate in design reviews and ADR discussions with the architecture team, bringing an implementer's perspective.
• Guide your team's data platform work at the integration boundaries between application work streams and the Microsoft Fabric data estate.

What You Bring

• 8+ years of professional software engineering experience, including 2+ years as a tech lead or equivalent — setting direction for other engineers, not just yourself.
• Expert-level C#/.NET — ASP.NET Core, REST API design, microservices patterns, and the judgment to know when not to use them.
• Strong Type Script/JavaScript skills with production React experience.
• Solid Azure and Kubernetes (AKS) experience — containers, deployment patterns, and CI/CD with…